The real issue, from my standpoint, is that the blood and volume of these kinds of dogmatic arguments drown out the very real discussion that could be going on. No matter where you go, there's usually about a dozen posters who have some valuable insight into running games, this design philosophy or that mechanical issue, but they rarely seem to have the kind of time on their hands that the people interested in no-holds-barred argument do.
I almost think the answer is to veer away from public discussion at all, and go toward either epistolary discussions displayed for the public, or podcasts, or maybe blog interactions, where you can select participants and screen for the kind of choleric interactions that cause so much trouble. I know that the most interesting stuff I've been seeing lately has been either in podcast form -- Ken Hite and Robin Law's podcasts, or the Unspeakable Oath podcast -- or in interviews, rather than forum discussions. There are exceptions, but forums seem to be of more and more limited utility, which seems to be a shame since they're unbeatable for general, public interaction.